In August I flew Delta One LHR to Philadelphia (757) and Salt Lake City to LHR (767). The 757 had a more private cabin feel as it's a 2-2 layout with the seats angled towards the windows, but I felt the seats were better on the 767 with the 1-2-1 layout where we opted for the middle two.
The IFE screens are large and clear, seats are comfortable (with arm rests on both sides) but the bed is harder than in UC as there's no flip over to a softer side. If you do fully recline while seated, you do have to do a bit of a shuffle as the seat is moving forward. I didn't like the pillow though as it wasn't breathable enough and got too hot with the side of my face on it.
The crew service was outstanding though. Plenty of attention, bottles of water, hot towels, drinks and food. You don't need to choose your starter as you get them all on a tray. All the food was very good, better than UC in my limited experience, and they were more than generous with the drinks. My wife's wine glass was kept topped up and I did like the way I was handed a second miniature bottle of Jack Daniel's Single Barrel to go with the one I'd had poured. I guess that's how the crew attempt to ensure everyone goes to sleep quickly.
With access to the CH and Revivals (if you land in time), I wouldn't hesitate to fly Delta One again.